Steam generator with flat combustion chamber bottom

ABSTRACT

In a steam generator having a combustion chamber defined by tubes forming a generally flat bottom wall and tubes forming upwardly extending side walls, means are provided in the general plane of the bottom wall forming entrance locations at which fluid medium enters the bottom wall tubes. The entrance locations are disposed substantially along vector lines arranged such that substantially all of the bottom wall tubes are each provided with two 90 degree turns in passing between its respective entrance location and said side walls and wherein the length of each of said bottom wall tubes is substantially equal.

May 7, 1974 United States Patent [191 Kral et a1.

[ STEAM GENERATOR WITH FLAT 3,457,903 3,259,109 7/1966 Grasme..........

COMBUSTION CHAMBER BOTTOM [75] Inventors: Rudolf Kral, Brauningshof;

Darlinger........... Brandstetter Primary ExaminerKenneth W. Sprague Attorney, Agent, or Firm-Herbert L. Lerner Mulheim Ruhr, Germany Oct. 30, 1972 [21] Appl. No.: 302,277

ABSTRACT [22] Filed:

In a steam generator having a combustion chamber defined by tubes forming a generally flat bottom wall 30 Foreign Application p i Data and tubes forming upwardly extending side walls, Oct 29 1971 means are provided in the general plane of the bottom wall forming entrance locations at which fluid medium enters the bottom wall tubes. The entrance locations Germany......... 2153965 52 US. 122/6 A, 122/235 A, 122/235 c 51 im. F22b 27/06 are dlspsed substam'any arranged such that substantially all of the bottom wall tubes are [58] Field of Search............ 122/6 A,

each provided with two 90 degree turns in passing between its respective entrance location and said side walls and wherein the length of each of said bottom wall tubes is substantially equal.

[56] References Cited UNITED STATES PATENTS 3,376,859 4/1968 Migzak 122/235 11 Claims, 10 Drawing Figures PATENTEDMAY H 4 3809.016

' mm 1 OF 3 HM F PATENTED MAY 7 I974 SHEET 2 BF 3 STEAM GENERATOR WITH FLAT COMBUSTION CHAMBER BOTTOM This invention relates to a steam generator of the type having a combustion chamber formed by suspended wall tubing in which adjacent tubes are welded gastight and wherein the tubes extend spirally upwardly on all sides, and further of the type having a flat or substantially flat combustion chamber bottom in which the tubing of the combustion chamber bottom extends to the side walls and continues as the side wall tubing.

In order to provide an arrangement of combustion chamber tubing which extends spirally upwardly on all sides of the combustion chamber and with direct transition or extension of the bottom tubes into the side wall tubes, while at the same time providing for uniform heat absorption of each tube and thereby largely preventing temperature differences between the individual tubes, it is important to make the length of the heated tubes in the combustion chamber bottom as equal as possible. This objective, however, presents difficulties, because in a large boiler there are a large number of parallel tubes and the individual tubes must form a gastight seal with adjacent tubes by providing finned tubes or by providing interposed welded straps. Accordingly, the bottom of the combustion chamber, like the side walls of the combustion chamber, is required to be provided with parallel tubes which, as far as possible, are arranged without gaps therebetween.

If the combustion chamber bottom is designed in the form of an ash funnel, the tube configuration of the combustion chamber side walls can usually be carried over readily into the area of the ash funnel. However, heretofore, it has always been necessary with flat combustion chamber bottoms to use intermediate manifolds so that the number of parallel tubes in the combustion chamber bottom could be chosen without restraint. If, however, the combustion chamber bottom tubes are to extend or be carried over directly into the side wall tubes, the number of the parallel tubes that must be accommodated in the combustion chamber bottom is predetermined. Also, the mutual spacing of the tubes can be varied only within narrow limits because only relatively slight differences exist as regards the individual tube pitches which are mainly determined by the width of the fins. The aforementioned problems are overcome by the present invention.

The present invention provides a central input distributor from which connecting tubes lead to entrance locations of the bottom tubes, which define the combustion chamber bottom wall. These entrance locations are situated in the general plane of the combustion chamber bottom tube wall and are arranged predominantly along vector lines originating from the center of the bottom wall and extending to a length equal to about one-half the length of the diagonal lines and extending at an acute angle relative to the diagonal lines. All the bottom tubes or substantially all of them extend to the outer edge of the combustion chamber bottom wall from the entrance location via two 90 degree turns in such a manner as to provide for heated tube lengths in the combustion chamber bottom which are all substantially equal. The entrance locations at the end of the vector or diagonal lines may also be arranged along an extension line which extends at an obtuse angle. The 90 degree turns may be effected by fittings, angles or elbows.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described in 5 relationship to specific embodiments, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a plan view and schematic representation of a combustion chamber bottom according to one embodiment of the invention with only portions of the bottom tubes which define the bottom wall being shown;

FIG. 2 is a schematic representation of a sectional view taken along the line IIII of FIG. 1;

FIG. 3 is an enlarged plan view of a portion of the bottom wall shown looking at the area of the lower portion of the lower vector line 14 shown in FIG. 1;

FIG. 4 is an enlarged plan view of a portion of the bottom wall shown looking at the area of the lower portion of the lower vector line 14 shown in FIG. 1;

FIG. 5 is a cross-sectional view taken along the line VV in FIG. 4;

FIG. 6 is a view similar to FIG. 4 but relating to an alternate embodiment;

FIG. 7 is a cross-sectional'view taken along the line VII-VII in FIG. 6;

FIG. 8 is an enlarged plan view of a portion of the bottom wall shown looking at the area of the upper portion of the upper vector line 15 shown in FIG. 1;

FIG. 9 is a cross-sectional view taken along the line IXIX in FIG. 8; and

FIG. 10 is a view similar to FIG. 8 but relating to an alternate embodiment.

Referring to the drawings, FIG. 1 shows a combustion chamber bottom of rectangular configuration as viewed from the top. The operating medium or fluid is fed to the tubes forming the combustion chamber bottorn by pipelines 1 and 2. An input distributor consisting of two sections 3 and 4 with an equalization line 5 therebetween is arranged underneath the bottom of the combustion chamber as can best be seen in FIG. 2.

Connecting tubes, for example connecting tubes 6, 7 and 8, 9, lead from the input distributor sections 3 and 4 to entrance locations, for example entrance locations 10, 11, 12 and 13 located in the general plane of the combustion chamber bottom. These entrance locations are situated predominantly on the vector lines 14 and 15. These vector lines are disposed at an acute angle, for example 14 degrees, relative to the respective diagonals which pass through the four corners of the rectangular combustion chamber bottom. In addition, extension tubes, for example tubes l6, l7 and 18, 19, also have further entrance locations disposed at the ends of the vectors 14 and 15. Each tube in the combustion chamber bottom has two turns of each extending from its entrance location to the outer edge of the com- By way of example, the tubing in the example of the illustrated embodiment may have 344 parallel tubes with a tube pitch of 52 mm. As will be seen from the drawings, particularly FIG. 1, the differences in lengths of the heated tubes in the combustion chamber bottom are only minor. As shown in FIG. 2, the tubes pass immediately at the edge of the combustion chamber bottom into the helical winding of the side walls.

FIG. 3 shows an enlarged section of a portion of the area along the lower portion of vector line 14 of FIG. 1. Tubes 20 to 28 extend vertically upwardly from below the combustion chamber bottom and are then formed with a turn or are otherwise bent to form the bottom tubing defining the combustion chamber bottom. It will be seen that all the feed tubes lie along the lines 14a and 14!). Tubes 29 to 32 extend vertically upwardly along the extension line 17. In the area of the combustion chamber bottom, all of the tubing is provided with fins so that gastight welding can be achieved between adjacent tubes.

The tube sections can be provided with fittings, angles or elbows to effect the necessary turns. In FIG. 4, and particularly in FIG. 5, which is a top view of a portion of the tubes looking along a lower portion of vector line 14, the use of fittings is shown to offset the turns. By use of these fittings, common fin tubes can be used for the combustion chamber bottom. These tubes are welded to the fittings in a simple manner. The fittings have fins of the same dimensions as the fins on the fin tubes.

In an alternate arrangement shown in FIGS. 6 and 7, tube elbows are used to effect the turns. Here, again, gastight welding of the entire tube bottom can be effected.

FIGS. 8 and 9 illustrate on an enlarged scale the use of forged angles and FIG. 10, the use of elbows. The tubes are provided with fins and it is possible also to obtain gastight welding of the tubes and elbows which form the combustion chamber bottom.

We claim:

1. In a steam generator comprising a combustion chamber having side walls and a bottom wall, bottom tubes defining a flat combustion chamber bottom wall, said bottom wall tubes extending to the edges of said bottom wall and continuing upwardly to form said combustion chamber side walls, means disposed below said bottom wall for feeding fluid medium to said bottom wall tubes, said means comprising a plurality of entrance locations disposed generally in the plane of said bottom wall and at which said fluid medium enters said bottom wall tubes, said entrance locations being disposed substantially along two substantially perpendicular vector lines which intersect generally at the center of said bottom wall, said bottom tubes being arranged and disposed such that substantially all of the bottom tubes are each provided with two 90 degree turns in passing between its respective entrance location and said side wall and wherein the lengths of each of said bottom wall tubes is substantially equal.

2. In a steam generator as set forth in claim 1 wherein said combustion chamber is of the type which is suspended from a boiler frame, said combustion chamber side wall being formed by side wall tubes extending spirally upwardly from said bottom wall, means joining adjacent bottom wall tubes and adjacent side wall tubes to one another to form gastight bottom and side walls.

3. In a steam generator as set forth in claim 1 wherein said means disposed below said bottom wall comprises a central input distributor and connecting tubes leading from said central input distributor to said entrance locations.

4. In a steam generator as set forth in claim 1 wherein said bottom wall is generally rectangular, said vector lines being disposed at an acute angle relative to diagonal lines connecting the corners of said bottom wall.

5. In a steam generator as set forth in claim 4 wherein said entrance locations extend along said vector lines a distance equal to approximately one-half the length of said diagonal lines.

6. In a steam generator as set forth in claim 1 wherein entrance locations are also arranged at the outer ends of said vector lines along an extension line disposed at an obtuse angle relative to the respective vector line.

7. In a steam generator as set forth in claim I wherein said degree turns are fittings.

8. In a steam generator as set forth in claim I wherein said 90 degree turns are tube elbows.

9. In a steam generator as set forth in claim 1 wherein said bottom wall tubes including said 90 degree turns are welded to form a gastight bottom wall.

10. Steam generator means comprising a substantially rectangular combustion chamber having walls and a bottom, a plurality gastight welded and upwardly extending tubes in said walls, a plurality of bottom tubes connected to said wall tubes, each tube of the combustion chamber bottom being so bent that it forms an angle of less than 45 with a wall of the combustion chamber, the entrance points of said bottom tubes situated in the said plane of the bottom being positioned on predetermined vector lines positioned substantially perpendicular to each other and intersecting substantially in the center of the bottom of the combustion chamber, said vector lines being located at an obtuse angle to the combustion chamber walls looking downwardly substantially 90 greater than the angle that said bottom tubes form with the walls of the combustion chamber at the junction of the wall and the bottom.

11. Apparatus as in claim 10, wherein the tubes of the combustion chamber walls leading to the entrance points on the bottom are so placed that they are deflected by 90, toward the center of the combustion bottomand so that they end when reaching one of said VBCILOI'S. 

1. In a steam generator comprising a combustion chamber having side walls and a bottom wall, bottom tubes defining a flat combustion chamber bottom wall, said bottom wall tubes extending to the edges of said bottom wall and continuing upwardly to form said combustion chamber side walls, means disposed below said bottom wall for feeding fluid medium to said bottom wall tubes, said means comprising a plurality of entrance locations disposed generally in the plane of said bottom wall and at which said fluid medium enters said bottom wall tubes, said entrance locations being disposed substantially along two substantially perpendicular vector lines which intersect generally at the center of said bottom wall, said bottom tubes being arranged and disposed such that substantially all of the bottom tubes are each provided with two 90 degree turns in passing between its respective entrance location and said side wall and wherein the lengths of each of said bottom wall tubes is substantially equal.
 2. In a steam generator as set forth in claim 1 wherein said combustion chamber is of the type which is suspended from a boiler frame, said combustion chamber side wall being formed by side wall tubes extending spirally upwardly from said bottom wall, means joining adjacent bottom wall tubes and adjacent side wall tubes to one another to form gastight bottom and side walls.
 3. In a steam generator as set forth in claim 1 wherein said means disposed below said bottom wall comprises a central input distributor and connecting tubes leading from said central input distributor to said entrance locations.
 4. In a steam generator as set forth in claim 1 wherein said bottom wall is generally rectangular, said vector lines being disposed at an acute angle relative to diagonal lines connecting the corners of said bottom wall.
 5. In a steam generator as set forth in claim 4 wherein said entrance locations extend along said vector lines a distance equal to approximately one-half the length of said diagonal lines.
 6. In a steam generator as set forth in claim 1 wherein entrance locations are also arranged at the outer ends of said vector lines along an extension line disposed at an obtuse angle relative to the respective vector line.
 7. In a steam generator as set forth in claim 1 wherein said 90 degree turns are fittings.
 8. In a steam generator as set forth in claim 1 wherein said 90 degree turns are tube elbows.
 9. In a steam generator as set forth in claim 1 wherein said bottom wall tubes including said 90 degree turns are welded to form a gastight bottom wall.
 10. Steam generator means comprising a substantially rectangular combustion chamber having walls and a bottom, a plurality gastight welded and upwardly extending tubes in said walls, a plurality of bottom tubes connected to said wall tubes, each tube of the combustion chamber bottom being so bent that it forms an angle of less than 45* with a wall of the combustion chamber, the entrance points of said bottom tubes situated in the said plane of the bottom being positioned on predetermined vector lines positioned substantially perpendicular to each other and intersecting substantially in the center of the bottom of the combustion chamber, said vector lines being located at an obtuse angle to the combustion chamber walls looking downwardly substantially 90* greater than the angle that said bottom tubes form with the walls of the combustion chamber at the junction of the wall and the bottom.
 11. Apparatus as in claim 10, wherein the tubes of the combustion chamber walls leading to the entrance points on the bottom are so placed that they are deflected by 90*, toward the center of the combustion bottom and so that they end when reaching one of said vectors. 